Project on Concrete Mix Design for various grades of Concrete
- Mix proportion of M35 grade concrete using fly ash as replacement of OPC .
1.Stipulations for proportioning
a) Grade designation : M35.
b) Type of cement : OPC 43 Grade conforming to IS 8112
c) Type of mineral admixture: Fly ash conforming to IS3812(part 1)
d) Maximum nominal size of aggregate: 20mm
e) Minimum cement content: 340kg/m^3(From table 5 IS456:2000-Exposure condition).
f) Maximum water-cement ratio: 0.45(From table 5 IS456:2000-Exposure condition).
g) Workability : 100mm for pumpable concrete.
h) Exposure condition: Severe for RCC.
i) Method of concrete placing: Pumping.
j) Degree of supervision: Good.
k) Type of aggregate: crushed angular aggregate.
l) Maximum cement content: 450kg/m^3.
m) Type of chemical admixture: Super plasticizers.
Test data for materials:
a) Cement used: OPC 43 Grade conforming to IS8112
b) Specific gravity of cement:3.15
c) Fly ash :Conforming to IS 3812 (part 1)
d) Specific gravity of fly ash: 2.2
e) chemical admixture: Superplasticizer conforming to IS9103.
f) Specific gravity of :
coarse aggregate: 2.74.
fine aggregate: 2.74.
g) Water absorption:
coarse aggregate: 0.5%.
fine aggregate: 1.0%.
h)Free surface moisture:
coarse aggregate: Nil
fine aggregate: Nil
i)Sieve analysis:
coarse aggregate: Conforming to table 2 IS 383
fine aggregate: Conforming to grading zone 1 of table 4 of IS 383.
3.Target strength for Mix proportioning.
F’ck=fck+1.65 s
F’ck= Target average compressive strength at 28 days.
Fck= Characteristic compressive strength at 28 days.
S= Standard deviation.
standard deviation from table 1 of IS10262:2009 is 5N/mm^2.
Therefore target strength =35+1.65*5=43.25N/mm^2.
- Selection of water-cement ratio:
From table 5 of IS456:2000 for severe exposure maximum water cement ratio is 0.45 .
- Selection of water content:
From table 2 of IS 10262:2009 ,Maximum water content for 20mm of aggregate is 186 l(for 25 to 50 mm)slump range
Estimated water content for 100 mm slump range =186+6/100*186=197 litres.
Based on trials water content reduction of 20% is achieved with plasticizers.
Hence the arrived water content =197*0.80=157.6 litre.
Take adopted water content =160 litre.
- Calculation of cement content:
Water -cement ratio =0.45
Cementitious material(cement +fly ash )content=160/0.45=355.55kg/m^3.
Fom table 5 IS456 minimum cement content for severe condition is 340 kg/m^3.
Which is less than obtained cement content hence ok.
Since fly ash is used cementitious content needs to be increased to improve workability and strength. The percentage of cementitious content increased depends on experience and research here it is increased by 10%
Cementitious material content= 355.55*1.10=391kg/m^3
Water -cement ratio=160/391=0.409
Fly ash @30%cementitous content=391*30%=117.3kg/m^3.
Cement(OPC)=391-117.3=273.7kg/m^3
Cement saved=355.5-273=81.85kg/m^3
- volume of coarse aggregate and fine aggregate:
From table 3 of IS 10262:2009 volume of coarse aggregate corresponding to 20 mm size of aggregate(zone 1 )for water cement ratio 0.45 =0.6.
(+/-0.01 for every +/-0.005)
So volume of coarse aggregate =0.61
For pumpable concrete the values are reduced by 10%
Volume of coarse aggregate = 0.61*0.9=0.55
Volume of fine aggregate = 1-0.55= 0.45.
8.Mix calculations
a) volume of concrete = 1m^3
b)volume of cement=( mass of cement /specific gravity of cement)*1/1000=273.7/3.15*1/1000=0.086m^3
c) volume of fly ash=( mass of fly ash /specific gravity of fly ash )*1/1000=117.3/2.2*1/1000=0.053m^3
d) volume of water=( mass of water /specific gravity of water)*1/1000=160/1*1/1000=0.160m^3
e) volume of chemical admixture=( mass of admixture /specific gravity of admixture)*1/1000=7.6*1.145*1/1000=0.006m^3
f) volume of aggregate (FA&CA)= a-( b + c + d + e )=1-(0.086+0.053+0.160+0.006)=0.695m^3
g) mass of coarse aggregate= f*volume of coarse aggregate *specific gravity of coarse aggregate *1000=0.695*0.55*2.74*1000=1047.365 kg/m^3
h) mass of fine aggregate= f*volume of fine aggregate *specific gravity of fine aggregate *1000=0.695*0.45*2.74*1000=856.935 kg/m^3
9.Mix proportion for trial no.1:
Cement= 278 kg/m^3
Fly ash= 117kgm^3
Water= 160kg/m^3
Fine aggregate = 857kg/m^3
Coarse aggregate = 1047kg/m^3
Chemical admixture = 7 kg/m^3
Water- cement ratio = 0.409
Trial mix ratio = cement :fine aggregate :coarse aggregate
= 278:857:1047
=1:3.08:3.76.
This trial mix ratio should match the workability, durability, minimum strength of M35 grade concrete.
If it does not satisfy two or more trials for increase of 10%water cement ratio should be done.
- Mix proportion of M50 grade concrete without using fly ash as replacement of OPC .
1.Stipulations for proportioning
a) Grade designation : M50
b) Type of cement : OPC 43 Grade conforming to IS 8112
c) Maximum nominal size of aggregate: 20mm
d) Minimum cement content: 360kg/m^3(From table 5 IS456:2000-Exposure condition).
e) Maximum water-cement ratio: 0.40(From table 5 IS456:2000-Exposure condition).
f) Workability :25 to 50mm.
g) Exposure condition: Extreme for RCC.
h) Degree of supervision: Good.
i) Type of aggregate: crushed angular aggregate.
j)chemical admixture type : superplasticizers.
- Test data for materials:
a) Cement used: OPC 43
b) Specific gravity of cement:3.15
c) chemical admixture: Superplasticizer conforming to IS9103.
d) Specific gravity of :
coarse aggregate: 2.74.
fine aggregate: 2.74.
e) Water absorption:
coarse aggregate: 0.5%.
fine aggregate: 1.0%.
f)Free surface moisture:
coarse aggregate: Nil
fine aggregate: Nil
g)Sieve analysis:
coarse aggregate: Conforming to table 2 IS 383
fine aggregate: Conforming to grading zone 1 of table 4 of IS 383.
3.Target strength for Mix proportioning.
F’ck=fck+1.65 s
F’ck= Target average compressive strength at 28 days.
Fck= Characteristic compressive strength at 28 days.
S= Standard deviation.
standard deviation from table 1 of IS10262:2009 is 5N/mm^2.
Therefore target strength =50+1.65*5=58.25N/mm^2.
- Selection of water-cement ratio:
From table 5 of IS456:2000 for extreme exposure maximum water cement ratio is 0.40 .
- Selection of water content:
From table 2 of IS 10262:2009 ,Maximum water content for 20mm of aggregate is 186 l(for 25 to 50 mm)slump range.
Based on trial water reduction of 20%is achieved with plasticizers, water content =186*0.80=148.8kg/m^3
Take adopted water content =150 kg/m^3
- Calculation of cement content:
Water -cement ratio =0.40
Cement content=150/0.40=375kg/m^3.
Fom table 5 IS456 minimum cement content for extreme exposure condition is 360 kg/m^3.
Which is less than obtained cement content hence ok.
- volume of coarse aggregate and fine aggregate:
From table 3 of IS 10262:2009 volume of coarse aggregate corresponding to 20 mm size of aggregate(zone 1 )for water cement ratio 0.40 =0.6.
(+/-0.01 for every +/-0.005)
So volume of coarse aggregate =0.62
Volume of fine aggregate = 1-0.62= 0.38.
- Mix calculations
a) volume of concrete = 1m^3
b)volume of cement=( mass of cement /specific gravity of cement)*1/1000=375/3.15*1/1000=0.119m^3
c) volume of water=( mass of water /specific gravity of water)*1/1000=150/1*1/1000=0.150m^3
d) volume of chemical admixture=( mass of admixture /specific gravity of admixture)*1/1000=7.6*1.145*1/1000=0.006m^3
e) volume of aggregate (FA&CA)= a-( b + c + d )=1-(0.119+0.150+0.006)=0.725m^3
f) mass of coarse aggregate= f*volume of coarse aggregate *specific gravity of coarse aggregate *1000=0.725*0.62*2.74*1000=1231.63 kg/m^3
g) mass of fine aggregate= f*volume of fine aggregate *specific gravity of fine aggregate *1000=0.725*0.38*2.74*1000=754.87 kg/m^3
9.Mix proportion for trial no.1:
Cement= 375 kg/m^3
Fly ash= 117kgm^3
Water= 160kg/m^3
Fine aggregate = 755kg/m^3
Coarse aggregate = 1232 kg/m^3
Chemical admixture = 7 kg/m^3
Water- cement ratio = 0.40
Trial mix ratio = cement :fine aggregate :coarse aggregate
= 1:2.01:3.28
This trial mix ratio should match the workability, durability, minimum strength of M50 grade concrete.
If it does not satisfy two or more trials for increase of 10%water cement ratio should be done.